New grinder with poorly machined burrs

Grinders are one of the keys to exceptional espresso. Discuss them here.
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Rostik_KIEV

#1: Post by Rostik_KIEV »

Hi! I bought Macap mc4. Grinder was absolutely new, unsealed. Examination of burrs under magnifying glass showed their bad state. A photo is added. Does it make any sense to require replacement of grinder or second replacement will appear the same?
Thank you.




Beezer

#2: Post by Beezer »

Those look pretty bad, especially if the grinder is supposed to be brand new. If I were you, I'd talk to the dealer about getting replacement burrs for free. If it's a good dealer, they should make it right.
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HB
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#3: Post by HB »

All the unused grinder burrs I've seen have flashing very similar to the third photo; they're worn off within a week's usage. To speed up the process for test grinders, HB sponsor Counter Culture thoughtfully provides five pounds of stale coffee to break the burrs in. I recommend running a few pounds of coffee through the burrs and make some coffee.

IMPORTANT: Do not overheat the grinder breaking it in. For example, grind for no more than 30 seconds and allow no less than 1 minute of rest. See the owner's manual for the maximum service duty.

For what it's worth, if I sold you the grinder, I would not accept a return based on the photos above. They do not appear significantly different from other unused burrs, e.g., like the new Mazzer burrs shown in Mazzer Mini Component Photos.

Dan Kehn

ira
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#4: Post by ira »

Depressingly, the quality of coffee grinder burrs that's I've see is poor at best.

Ira

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JonR10

#5: Post by JonR10 »

It's terrible, isn't it?

Most espresso grinder burrs have shockingly poor finishing from the machine operations. Whenever I get a new set now I use my very fine files to carefully remove the hanging edges before installing the new burrs into a grinder, but I still grind through a few pounds of coffee before using for espresso.
Jon Rosenthal
Houston, Texas

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cafeIKE

#6: Post by cafeIKE »

It's only terrible if it matters. Have blind tests proven that filed burrs perform better?
(Relax, it's HUMOR :wink: )

A new set of burrs takes about 2 kilos to settle, adding about $75 to the cost.

The burrs could be machined perfectly for how much $$$ more?
Would the customer pay 10x to save 1kg? 100x to save 1.5kg? 1000x to save 1.75kg?

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JonR10

#7: Post by JonR10 »

You should know better (probably do), and I should know better than to respond. But I choose to type this so that off-the-charts exaggeration of deburring cost can be corrected.

We generously plan 5-10 minutes to deburr parts of this size and complexity after machining, not even close to a 10x cost increase (more like $2-$5 per set at our shop rate). In our business, even if we didn't add the operation to the router our machinists would deburr the parts out of pride in workmanship.

And if we want to justify the $2 cost, what if it takes just a pound or two for the break-in of properly finished burrs as opposed to your $75 for two kilos of coffee? I have heard estimates up to 10-20 pounds to properly break in commercial burrs which strikes me as ridiculous, but probably necessary because we're deburring machined plates with coffee beans instead of using a deburring tool (or a small file).

That is TERRIBLE workmanship, period. I showed some new Super-Jolly burrs to the machinists in one of our shops one time...they laughed out loud and ridiculed the finishing work. :lol:
Jon Rosenthal
Houston, Texas

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HB
Admin

#8: Post by HB »

cafeIKE wrote:It's only terrible if it matters. Have blind tests proven that filed burrs perform better?
While I don't have blind taste tests to confirm, my experience and the corroboration of others confirms that there is a "break in" period for new burrs; the symptom is a drifting grind setting during the first couple days of use. Whether it requires 1 pound, 2 pounds, or 10 pounds is another matter. For test purposes, I grind at least 5 pounds, but it's a guess.
JonR10 wrote:...And if we want to justify the $2 cost, what if it takes just a pound or two for the break-in of properly finished burrs as opposed to your $75 for two kilos of coffee?
Not to excuse the lack of attention to deburring, but let's keep things in perspective. In a busy cafe, a new set of burrs probably last a couple months, maybe longer. In a home barista's kitchen, the same burrs would last 5-10 years. Sacrificing a few pounds of stale coffee and the 10-15 minutes it takes to break in a new set doesn't strike me as a terrible burden.

Back to the original question, regrettably the burrs depicted in the first post are typical of new burrs. With enough badgering, Rostik may be able to convince the seller to accept them as defective, if only to settle the matter. I would instead scrounge up some stale coffee, grind it, and move onto shot pulling.
Dan Kehn

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shadowfax

#9: Post by shadowfax »

I would love to blind test this. Little edges of 'flashing' that can be de-burred are one thing; I see conical burrs with notching on them... brand new. You can't file that out. Again, I'd love to blind test this if someone could just point to a place to get premium quality made burrs.
Nicholas Lundgaard

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JonR10

#10: Post by JonR10 » replying to shadowfax »

Making the little cone with exterior cutting edges is not too much of a problem, but the donut with interior cutting edges will be cost-prohibitive for just one or two (or a few). If we could organize a run of hundreds it might be viable and I know the folks to do the work....but we'd need to commit a large quantity to get anywhere near a reasonable price.

That said, those little notches and imperfections may not affect the grind at all if the main controlling factor for grind quality is the annulus between the inner and outer burrs at the tightest spot. It seems likely to me that everything going on before the beans reach the final edge of the burrs (i.e. about to leave the grind path) is rough crushing and breaking and the only precision grinding happens at the small space at the end of the grind path just as the particles are getting ready to exit the burrs.

There is a logical follow-on to this notion....
Jon Rosenthal
Houston, Texas